共查询到20条相似文献,搜索用时 93 毫秒
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Feng WEI* Ling Yun MA Yan LIU Rui Chao LIN Division of Chinese Materia Medica Natural Products National Institute for the Control of Pharmaceutical & Biological Products State Drug Administration Beijing 《中国化学快报》2002,13(1)
Aesculus chinensis is a traditional chinese medicinal plant widely distributed in China, which has been used to treat stomach disease. From recent research its seeds contain many flavonoids and proanthocyanidin A2, which have potential venotonic and vasoprotective action and powerful antioxidant activity. In this paper, we report the isolation and the structure elucidation of a new flavonol oligosacchride. Bioassay results showed that the compound exhibited an antivirus activity. … 相似文献
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以Eu(hfc)3和Pr(hfc)3为手性镧系位移试剂(CLSR),比较了两种CLSR对2,4-滴丙酸甲酯的1HNMR和13C NMR谱手性分离效果,结果表明:Pr(hfc)3比Eu(hfc)3对手性中心相连的甲基具有更好的手性分离效果。首次应用Pr(hfc)3测定了盖草能、稳杀得和喹禾灵3种手性芳氧丙酸酯类除草剂的1HNMR和13CNMR谱,其1HNMR谱分离度R约为1,盖草能和喹禾灵的13C NMR谱分离度R大于1.5,说明1H NMR和13CNMR谱手性分离效果适用于对映体纯度测定。与手性色谱法相比,CLSR-NMR法测定对映体纯度具有操作简便、分析速度快的显著优势。 相似文献
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用^3HNMR波谱法分析微波激发催化交换制备的^3H标记颠茄类生物碱 总被引:1,自引:0,他引:1
用~3H NMR波谱法测定了微波激发催化交换制备的四种~3H标记颠茄类生物碱示踪剂的氚标记位置及其相对百分含量。并在用~1H NMK归属原料纯度及标记物分子各基因化学位移时采用了水峰抑制技术(简称WEFT),既能同时消除溶剂氘代甲醇及水峰的影响;又能提高灵敏度(近10倍),从而计算出所得标记产物的化学纯度值与放化纯度值。为快速、准确寻找制备标记生物碱的最佳实验条件和控制标记物质量提供了唯一的物理无损分析方法。 相似文献
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通过Adole反应和Grigard反应合成了相应的两种立体异构的1,3,5-三-α-萘基苯. 报道了它们的UV, IR, FD-MS和NMR . 论了两种异构体的^1H NMR 和^1^3C NMR的区别. 相似文献
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K Fujiwara K Komatsu G W Wang T Tanaka K Hirata K Yamamoto M Saunders 《Journal of the American Chemical Society》2001,123(43):10715-10720
Cyclopropanation with diethyl bromomalonate and base (the Bingel reaction) was conducted on fullerene dimer C120 to give a mixture of "monoadducts" (45% yield) and "bisadducts" (< or =37% yield), while 18% of the C120 remained unchanged. The "monoadducts" were separated into five positional isomers, i.e., e(face), e(edge), trans-4, trans-3, and trans-2, by preparative HPLC. Assignments were made based on 1H (and 13C) NMR and confirmed by theoretical calculations of the addends' 1H NMR chemical shifts. The relative yields of these isomers were in fair agreement with those observed for the Bingel bisaddition of C60. The Bingel reaction was also carried out on the dimer C120 encapsulating 3He in one of the C60 cages. Each positional isomer of the "monoadduct" exhibited a pair of 3He NMR signals corresponding to an isomer with functionalization on the 3He-containing cage and the other isomer with functionalization on the empty cage. Using the 3He NMR spectroscopy, a pair of signals for the trans-1 isomer, which eluded detection by 1H NMR, were observed, in addition to pairs of signals for e(face), e(edge), trans-4, trans-3, and trans-2 isomers. The 3He NMR signals for isomers with functionalization on the 3He-containing cage were spread out over a 1.82-ppm range reflecting the direct effects of the addition pattern on the C60 surface. In contrast, the isomers with functionalization on the empty cage exhibited 3He NMR signals that appeared over a 0.14-ppm range, which was shown to be primarily due to changes in the diamagnetism of the functionalized cage based on theoretical calculations of 3He NMR chemical shifts for the model system in which the C60 cage encapsulating 3He was removed. 相似文献
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Trachylobagibberellin类似物的化学合成研究(Ⅰ)──12.16R-环赤霉低酸甲酯的合成谢文革,崔育新,马建泰,潘鑫复(兰州大学化学系,兰州大学应用有机化学国家重点实验室,兰州,730000)关键词Trachylobagibbere... 相似文献